THE AREAS OF INVESTIGATION: 1. Cytogenetic studies of human neoplastic, hematological, and congenital diseases and of members of high-risk cancer families. 2. Observation of chromosomal aberrations and teratogenic effects of mitotic inhibitors, such as azarbine, vincristine, colchicine, maytansine and other Phase I drugs using in vivo and in vitro techniques. 3. In vitro cytogenetic studies of direct tumor material and tissue culture lines established from patients with Burkitt's lymphoma. 4. Detection of sister chromatid exchanges in families with ataxia telangiectusia and Bloom's syndrome.